Camera cranes are often used in motion picture and television production. The motion picture or television camera is typically mounted on a crane arm supported on a mobile base, dolly, or truck. The mobile base may be pushed and steered by hand. Larger units, which have more weight carrying capacity, and longer reaches, typically have electric driving motors powered by onboard batteries. Some mobile bases also including conventional gasoline or diesel engines, may also serve as over the road vehicles.
Camera cranes generally have a crane arm supported on a base, with a camera platform at one end of the arm, and a counter weight at the other end. The crane arm can be pivoted by hand to raise and lower the camera, and also to pan to the left or right side. A leveling system is often included to maintain the camera platform in a level orientation, as the elevation angle of the arm changes. Some mobile bases may include a self leveling or an extendible center post or column, which the crane arm can be mounted on. Even with use of existing leveling systems, under certain conditions, unintended or undesirable camera movements may still occur, due to strain on leveling cables or other crane components, when under high loads. The payload carried by the camera platform, includes the camera, the lens, associated camera accessories such as remote control units, batteries, etc., and any camera head or riser. Accordingly, the payload may exceed 100 pounds, even when using a lightweight camera.
The center of gravity of the payload is almost always displaced from the center of the crane arm. Accordingly, when the payload is accelerated, by movement of the crane arm, or the mobile base supporting the crane, inertial forces act to deflect the camera platform from the desired level position. The camera platform may also be displaced from level by wind forces, additional weight temporarily placed on the platform, hand forces applied by the crane operators, etc. These kinetic factors cause unwanted movement of the lens, which can disrupt the filming or video recorded images. While existing stabilizing systems have met with varying degrees of success, problems remain in providing a stabilizing system able to quickly, accurately, and smoothly counteract the kinetic deflections of the camera platform, without degrading overall crane performance via added weight, bulk, power consumption, or reliability.
Accordingly, various engineering challenges remain in designing a stabilizing system for use in a camera crane.